JPH0661548A - Magnetoresistance transducer - Google Patents

Abstract

PURPOSE: To obtain a symmetric track profile to improve the response at the edge of the track in a magnetoresistive transducer usable in magnetic discs, etc. CONSTITUTION: Conductors 32, 34 are disposed so that the magnetic fields H in the conductors to feed/discharge a current to/from a magnetoresistive element 36 are uniform as well as the areas of the conductors exposed to air bearing surfaces are minimized.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to magnetoresistive transducers. More specifically, the present invention relates to improvements in conductor configurations for magnetoresistive transducers.

[0002]

2. Description of the Related Art With the continuous development of magnetic media technology, it is possible to increase the data storage density. One of the active development areas is the area of high power read transducers. As the size of this type of transducer becomes smaller, the data density increases. Magnetoresistive (MR) thin film technology has provided a promising area of research, especially for the fabrication of smaller read transducers. The conductive thin film in this type of technology is formed on the substrate using techniques similar to those in semiconductor technology.

The MR stripe or element in a single-stripe MR transducer (or two MR stripes or elements of a dual-stripe MR transducer, such as disclosed in US Pat. No. 3,860,965 issued to Voegeli) is used for magnetic media. Must be long compared to the track width. In this way, the transducer provides a stable region condition. Various configurations have been proposed to contact the MR stripe to provide power to the stripe and to sense magnetic flux (ie, data) using the MR stripe.

In one prior art conductor configuration of the type shown in FIGS. 1A and 1B, each MR stripe 16 is shown.
It comprises two conductors 12, 14 for contact with. In the figure, the current direction is indicated by "i", the magnetic field direction is indicated by "H", and the magnetization direction is indicated by "M". These display methods are
It shall apply throughout this application.

In the structure shown here, since the conductor is arranged on the MR stripe, the conductor upper structure (conducto) is used.
rs-over arrangement) and is used for a bias MR head having a shape like a spiral signboard of a barber shop. The conductor superstructure is susceptible to shorts with the transducer shield (not shown) or the other MR stripe (for a bi-stripe MR transducer). This kind of short circuit
Either due to conductor contamination in the lapping process used to form the air bearing surface of the transducer, or due to encountering disk surface roughness within a working disk drive.

The length of the conductor along the air bearing surface of the transducer has a very important meaning. Figure 1
The length of the conductor in (a) is about 400 μm at the longest and about 40 μm at the shortest. The longer this dimension is,
Between the transducer shield (not shown) and the MR conductor, or in the case of a bi-striped transducer, as a result of lapping the transducer air bearing surface, or contact with the rough portion of the disk as previously described. Is likely to cause a short circuit between the two MR conductors.

The arrangements discussed in the prior art, shown in FIGS. 2 (a) and 2 (b), are properly tip arrangements.
t). The chip transducer is a conductor 2 arranged to pass a current to the MR element 26.
2 and 24. It is well known that this is a configuration developed by International Business Machines in Armonk, NY, USA. Experience with those who use tip-mounted transducers tends to result in non-uniform response at the track edges in this type of configuration. This is partly because at the edge of the conductor (track edge), the magnetic field "H" is applied in different directions by the current "i".

In FIG. 2 (a), the direction of the magnetic field "H" induced by the current "i" is not the same, even if this current does not bend the magnetic field at the edge of the track. Therefore, the magnetization "M" rotates non-uniformly at the edges of the track. Therefore, the responses occurring at the edges of the tracks are not the same, resulting in an asymmetric track profile.

Similarly, to reproduce high track densities with one single area MR transducer, M
The length of the R element (or elements in the case of a bi-stripe transducer configuration) must also be much larger than the width of the track. One way is to get high resolution along the track by M
The MR sensor part of the R transducer is placed between two magnetic shields. In an MR read element, the active portion is defined as the portion of the MR element through which the sense current flows and is generally determined by the placement of conductor leads in and out of the MR element. The reed and MR element together form a single turn coil that causes an unwanted inductive response to the recorded information. The magnitude of this response is determined by the number of tracks covered by this type of coil.

Therefore, the current state of the art for MR transducers has various problems associated with conductor placement. These problems include low yield due to short circuits, poor track profile symmetry due to lack of uniform magnetic field at the track edges, and inductive pickup due to inductive inter-track interference. The problem of is included.

[0011]

The present invention is directed to a magnetoresistive transducer that is improved to minimize, if not completely eliminate, the problems of short circuits, lack of symmetry at the edges of tracks, and picking up signals by induction. It is intended to provide an arrangement of current conductors.

[0012]

SUMMARY In a preferred embodiment of the present invention, conductor configurations for single-stripe or bi-stripe transducers are provided. In this conductor configuration, the magnetic fields in the conductors are oriented in the same direction, giving a symmetrical track profile, which improves the response at the edges of the tracks. The conductor portion at the air bearing surface is also minimized to reduce the possibility of short circuits, thereby improving device yield and reliability.

In one embodiment of the present invention, the conductive configuration limits the width of the active portion of the magnetoresistive sensing element to minimize inductive pick-up. Another embodiment of the invention, useful in applications involving bi-stripe magnetoresistive transducers, is to arrange conductors on top of each other for each magnetoresistive stripe,
Inductive pick-up is minimized by differentially coupling these conductors by common mode rejection to cancel the inductive pick-up.

[0014]

The present invention is best understood by considering the description of the embodiments with reference to the drawings. The present invention provides a unique conductor configuration for a magnetoresistive (MR) transducer. By applying the disclosure of the present invention, it is possible to manufacture various types of MR transducers, and the MR transducers manufactured in this way all have a symmetrical track cross-sectional shape, and are capable of being picked up by induction. There is little risk of causing a short circuit due to contamination during the lapping process.

In the configuration of the MR transducer shown in FIG. 3, the MR element is used to pass a current between the MR element and the MR element.
The conductors 32 and 34 are arranged so as to contact the element 36. These conductors are generally L-shaped, with the wider portion of the "L" contacting the MR element. In the conductor shown in the figure, the conductor width of the conductor portion connected to the MR element is 5 μm to 25 μm, and the conductor width of the conductor portion overlapping the MR element is 2 μm to 5 μm.
Is preferably up to.

In the figure, the current "i" flowing in the conductor is indicated by an arrow. Thus, current flows into the MR element by conductor 32 and out of the MR element by conductor 34, providing a uniform current injection into the MR element. As shown, an important property of the invention is that the direction of the magnetic field "H" in the conductor is the same due to the current in the conductor at the edge of each track. Thus, the present invention provides a uniform magnetic field at the track edges. This fact is important for maintaining a symmetrical track profile without adversely affecting the response at the track edges. The magnetization "M" is shown as a diagonal line across the active portion of the transducer.

FIG. 3 (b) shows the transducer air bearing surface of the present invention. Where conductors 32 and 3
The cross section of No. 4 is a narrow trapezoid with a taper shape. Note that this narrow cross-section gives a very small conductor surface to the air bearing surface of the transducer. Therefore, when lapping the transducer to create the air bearing surface, the conductor is less likely to become contaminated and short circuit with other transducer components. Moreover, the small area occupied by the conductors manufactured in accordance with the present invention results in very low inductive pick-up, as will be discussed in more detail below. It should be noted that the above discussion was made for a conductor superposed transducer, where the direction of magnetization was shown to be biased. The present invention is not limited to the exemplary embodiments discussed above, but conductors underneath the MR element and other types of elements may also be used in the practice of the invention. Furthermore, the invention does not depend on the method used to bias the MR element. This configuration can be used for dual stripe MR transducers as well.

According to another aspect of the present invention, the detection element (M
The MR transducer (or other solid state sensor, such as a Hall effect device) for electrical contact that minimizes inductive pick-up due to the nature of the single turn coil of the R element) and its electrical leads.
Is to give to. When using a differential sensor, such as a dual element MR sensor, the present invention provides a means of eliminating inductive pick-up and significantly reducing track-to-track interference.

FIGS. 4 (a) to 4 (d) are plan views of examples in which the conductor arrangement according to the present invention is applied to various MR transducer configurations. Figure 4 (a)
Means that the conductors 42, 43 contact the MR element 44,
2 shows a conductor configuration for a MR sensor structure in the shape of a barbershop spiral sign. In the figure, the tracks on the magnetic medium are arranged as indicated by a broken line 45. Here, the portion of the broken line 45 where the line exists indicates the track, and the broken portion of the broken line 45 indicates the separated portion between the tracks. Figure 4
The relative position of the track to the active portion of the transducer shown in (a) is the same in FIGS. 4 (b) and 4 (c), but is shown only in FIG. 4 (a) for the sake of simplicity.

In the configuration shown in FIG. 4A, the conductors are placed close to each other with a small spacing between them to minimize the width of the active portion of the sensor, thereby minimizing inductive pick-up. . In this way, if the sensor is located on one track, it will effectively detect neither MR response nor inductive response to adjacent tracks.

FIG. 4 (b) shows the conductors 42a, 43a arranged in contact with the MR element 44a. The arrangement shown here is a soft adjacent layer.
It has been applied to (SAL biased) MR transducers. The operation of the embodiment shown in FIG. 4B is as shown in FIG.
Is the same as in. Therefore, a spacing is placed between these conductors to limit the active area to the selected tracks and to minimize inductive pick-up.

FIG. 4 (c) shows a conductor array that can be used in a bi-stripe MR transducer. Conductors 46, 47
Of the MR element 50 is in contact with the first pair of MR elements 50 and the second pair of conductors 48, 49
Are arranged in contact with the second element of the pair of MR elements. In this configuration, the MR elements are co-located, i.e. one element overlying the other. Figure 4
In the configuration of (c), the conductor pairs are arranged close to each other to limit the active area of the detection element. In addition, a differential output is produced by sensing with each sensing element, which, when combined with the differential signal, cancels the inductive pick-up by common mode rejection. This type of differential detection operation is performed by a double stripe MR.
Useful in the case of a transducer (see, eg, US Pat. No. 3,860,965 granted to Voegeli). What is important is that the differential signals cancel each other out only if the MR stripes are of the same nature, that is, they cover the same area both in terms of their range and their position.

The structure of another embodiment of the present invention is shown in FIG. In this configuration, the bi-striped MR transducer has two MR detector elements 50a connected to each other.
It has one conductor pair 46a / 47a, 48a / 49a.
In this embodiment of the invention, the MR element is shown in FIG.
Similar to the embodiment of (c), they are arranged on top of each other, but since magnetic fields from a large number of tracks are detected, pick-up by induction from each MR element is relatively large. However, these fields are detected by the MR element in combination and the two element signals are subtracted from each other when differentially coupled. Thus, the conductor pattern covers virtually the same area in area and position with respect to the track, so the net inductive pick-up is almost zero. Therefore, as long as the conductivity of the conductor lead is at least 10 times the conductivity of the MR element to which it is connected, the response of the MR element is substantially limited to the track on which the sensor is centered. To be done.

5 (a) to 5 (c), the outputs of the MR elements are differentially connected, the active region is located at the center of the first track "B", and the adjacent track "A" is Figure 3 shows an example of a bi-stripe MR transducer placed along one conductor of the transducer. The example of FIG. 5 (a) illustrates one embodiment of the present invention in operation. In all three of these cases, the MR active region is the same and M
There is no R element offset.

FIG. 5A shows a book having a first conductor pair 51, 53 and a second conductor pair 52, 54 connected between two MR elements (not shown) and a differential amplifier 57. A preferred embodiment of the invention is shown. The transducer active area 59 is shown centered on track "B". In the figure, these single turn coils made up of a combination of conductors and MR elements have the same area and are overlapping. In operation, in this configuration, the MR response of reading data for track "B" is high, while the inductive response is canceled. Further, in this configuration, neither MR response nor inductive response is given to the track "A".

FIG. 5B shows two MR elements 68.
And a first conductor pair 61 connected between the differential amplifier 67 and
63 and a second conductor pair 62, 64 are shown. The center of the transducer active area 69 is located on track "B". In the figure, single-turn coils made up of a combination of conductors and MR elements have the same area but are not overlapping. In this operation, in this configuration, the MR response of the data read to the track “B” is high, but the inductive response from the track “B” is canceled. Further, in this configuration, there is no MR response for track "A". In this configuration, the magnetic flux penetrates the coil formed by the first MR element and its associated conductor leads, thus producing some inductive response to track "A", while Is the second M
Little or no penetration is made through the coil formed by the R conductor and its associated conductor lead. This configuration causes non-repetitive guided pickup.

FIG. 5C shows two MR elements 78.
And a first conductor pair 71 connected between the differential amplifier 77 and
73 and a second conductor pair 72, 74 are shown. The active area 79 of the transducer is shown with its center located on track "B". In the figure, these single-turn coils made up of a combination of conductors and MR elements have different parts and are not offset. In this operation, the MR for reading the data on the track "B" is used in this configuration.
The response is high, but the inductive response from track "B" is canceled. In this configuration, the magnetic flux penetrates the coil formed by the first MR element and its associated conductor leads, thus producing some inductive response to track "A", while the magnetic flux Little or no penetration is made through the coil formed by the second MR conductor and its associated conductor leads. This configuration also causes non-repetitive guided pickup.

The above examples discussed with respect to FIGS. 5 (b) and 5 (c) show two conductor configurations which are unacceptable in that the inductive pick-up is not suppressed. Therefore, these configurations do not meet the criteria of the present invention, namely the reduction or elimination of guided pickup. Overall, one preferred embodiment of the present invention is the configuration shown in Figure 5 (a), as previously discussed. In particular, for bi-stripe MR transducers, the preferred embodiment of the present invention uses the conductor shown in FIG. 3 (a) in the configuration shown in FIG. 4 (d).

Although the present invention has been described with reference to the preferred embodiments, those skilled in the art can readily substitute other configurations and applications than those described above without departing from the spirit and scope of the invention. You should understand. Accordingly, the invention should only be limited by the claims included below.

[0030]

As described in detail above, according to the present invention, a symmetrical track profile is obtained and the response of the edge of the track is improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of a conductor configuration according to a conventional technique.

FIG. 2 is a diagram illustrating another example of a conductor configuration according to the related art.

FIG. 3 is a diagram illustrating a conductor configuration according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating a conductor configuration according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a conductor configuration according to an embodiment of the present invention.

[Explanation of symbols]

12, 14: Conductor 16: MR stripe 22, 24: Conductor 26, 44: MR element 32, 34, 42, 43: Conductor 36, 44a, 50a, 68, 78: MR element 42a, 43a, 46, 47, 51 , 52, 53, 5
4, 61, 62, 63, 64, 71, 72, 73, 7
4: conductor 57, 67, 77: differential amplifier

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Robert Jay Davidson Eagle Steelwell Drive, Idaho, USA 1156 (72) Inventor Victor W. Hesterman Los Altos Hills Canario, USA Way 12715 (72) Inventor Lung Te Trang Saratoga, California, United States 5085 (72) Inventor Guiola Jay Tarnopolskiy Palo Alto Jackson Drive, CA 525

Claims (9)

[Claims] 1. A magnetoresistive transducer having the following (a) and (b) and having an air bearing surface: (a) at least one magnetoresistive element; (b) carrying an electric current to and from the magnetoresistive element. Conductor: The conductor constitutes a small conductor area at the bearing surface, and the magnetic field along the conductor runs in the same direction. 2. The magnetoresistive transducer according to claim 1, wherein the conductor has a conductor upper structure. 3. The conductor has an L-shaped configuration when viewed from above and has a narrow taper profile when viewed from the air bearing surface. Magnetoresistive transducer as described. 4. The conductor is 5 μm to 25 μm of 2 μm
L overlying the magnetoresistive element with a width of .about.
Magnetoresistive transducer according to claim 3, characterized in that it comprises an additional portion of a letter-shape and a relatively narrow lead portion. 5. A magnetoresistive transducer comprising the following (a) and (b): (a) at least one magnetoresistive element; (b) carrying an electric current with the magnetoresistive element. At least two conductors: The at least two conductors are arranged slightly apart to cover a minimum area, limiting the active area of the transducer to a defined track area. 6. The transducer forms a spiral signboard shaped sensor of a barber shop.
Magnetoresistive transducer as described. 7. A magnetoresistive transducer according to claim 5, comprising a SAL biased transducer. 8. A double-stripe magnetoresistive transducer characterized by comprising the following (a) and (b): (a) at least two magnetoresistive elements; (b) a current flowing between the magnetoresistive elements. A conductor pair carrying the conductors: the conductor pairs are arranged so as to overlap one another. 9. The magnetoresistive transducer of claim 8 wherein each said pair of conductors has the same area and is overlapping.